<head>
<title>Polyconic</title>
</head>
<body>

<h1>Polyconic</h1>

<table border>

<td>Name
<td>Polyconic
<tr>

<td>EPSG Code
<td>
<tr>

<td>GeoTIFF Code
<td>CT_Polyconic (22)
<tr>

<td>OGC WKT Name
<td>Polyconic
<tr>

<td> Supported By
<td> GeoTIFF, GXF, OGC WKT
<tr>

</table>

<h3>Projection Parameters</h3>

<table border>
<th>Name
<th>EPSG #
<th>GeoTIFF ID
<th>OGC WKT
<th>Units
<th>Notes

<tr>
<td> Latitude of false origin
<td> 1
<td> NatOriginLat
<td> latitude_of_origin
<td> Angular
<td>

<tr>
<td> Longitude of false origin
<td> 2
<td> NatOriginLong
<td> central_meridian
<td> Angular
<td>

<tr>
<td> Scale factor at natural origin
<td> 5
<td> ScaleAtNatOrigin
<td> (not included)
<td> Unitless
<td>

<tr>
<td> Easting of false origin
<td> 6
<td> FalseEasting
<td> false_easting
<td> Linear
<td>

<tr>
<td> Northing of false origin
<td> 7
<td> FalseNorthing
<td> false_northing
<td> Linear
<td>

</table>

<h3>Notes</h3>

In Geosoft GXF format it is known by the name "*Polyconic"
indicating that it isn't an EPSG projection.<p>

Discussions on the GeoTIFF mailing list a few years suggested that this
projection should use ProjCenterLat and ProjCenterLong instead of 
NatOriginLat and NatOriginLong.  Intergraph uses natural origin, and PCI
uses ProjCenter as I believe does Erdas.<p>

<h3>PROJ.4 Organization</h3>

<b>
<pre>
  +proj=stere +lat_0=<i>Latitude at natural origin</i> 
              +lon_0=<i>Longitude at natural origin</i>
              +x_0=<i>False Easting</i>
              +y_0=<i>False Northing</i>
</pre>
</b>


</body>
